chore(kumactl) add command argument count parameters

[jpeach]

Summary

Add cobra argument count specifiers to all the kumactl subcommands. This
improve command-line validation and lets cobra emit better error messages.

Full changelog

• Improved kumactl argument validation.

Issues resolved

N/A

Documentation

N/A

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[bartsmykla]

lgtm

[codecov-commenter]

Codecov Report

Merging #3010 (dedc4c9) into master (21b0d4d) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3010      +/-   ##
==========================================
+ Coverage   52.27%   52.30%   +0.03%     
==========================================
  Files         913      913              
  Lines       52857    52871      +14     
==========================================
+ Hits        27630    27656      +26     
+ Misses      23026    23011      -15     
- Partials     2201     2204       +3     

Impacted Files	Coverage Δ
app/kumactl/cmd/apply/apply.go	75.00% <100.00%> (+0.26%)	⬆️
app/kumactl/cmd/completion/completion.go	100.00% <100.00%> (ø)
...pp/kumactl/cmd/config/config_control_planes_add.go	81.94% <100.00%> (+0.25%)	⬆️
...p/kumactl/cmd/config/config_control_planes_list.go	100.00% <100.00%> (ø)
...kumactl/cmd/config/config_control_planes_remove.go	91.66% <100.00%> (+0.36%)	⬆️
...kumactl/cmd/config/config_control_planes_switch.go	90.00% <100.00%> (+0.52%)	⬆️
app/kumactl/cmd/config/config_view.go	84.61% <100.00%> (+1.28%)	⬆️
app/kumactl/cmd/generate/generate_certificate.go	78.94% <100.00%> (+0.56%)	⬆️
...p/kumactl/cmd/generate/generate_dataplane_token.go	94.44% <100.00%> (+0.15%)	⬆️
app/kumactl/cmd/generate/generate_signing_key.go	93.75% <100.00%> (+0.20%)	⬆️
... and 6 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 21b0d4d...dedc4c9. Read the comment docs.